1. Field of the Invention
This invention relates to a portable information terminal displaying not only an image on a screen of a fixed display part attached to a front of a case but also an image on a screen of a movable display part provided on a back of the case.
2. Related Art of the Invention
The portable information terminal is a battery-driven electronic communication device that has a battery in its body. As a general portable information terminal, a portable telephone, a PDA (personal digital assistant) and the like are cited.
In the field of portable telephones among conventional portable information terminals, there is a portable telephone in which a camera can be built or to which a camera can be attached externally. Moreover, there is also camera capable of photographing not only a still image but also a motion image. Presently, the portable telephone is highly computerized and made to have multiple functions. Thus, there is an urgent need to enlarge a display area of a screen and to improve a display efficiency.
As a well known example in the past related to a portable telephone with a video telephone function, in Japanese Patent Application Laid-open No. Hei 10-65780, disclosed is a portable telephone including a video camera and an image display part inside a body, the image display part displaying a received image and a transmitted image, in which an image to be transmitted and received is displayed on the same screen.
Moreover, as a method of enlarging a display area, in Japanese Patent Application Laid-open No. Hei 9-247250, disclosed is a portable telephone including a lid body in a shape of encasing an operating part, in which the lid body can be opened and displays a large amount of information as one color liquid crystal display composed of two screens when opened.
Furthermore, in Japanese Patent Application Laid-open No. 2001-136247, disclosed is a folding portable telephone capable of confirming reception of a mail and the like even in its folded state by attaching a display part thereto, which is exposed to the outside of the portable telephone in a state of folding a case.
In the field of portable video telephone sets among the portable information terminals, as a technique of displaying a transmitted image, in Japanese Patent Application Laid-open No. Hei 11-146370, disclosed is a technique in which a single display screen is displayed by being divided into two screens when used as a video telephone and is displayed without any division thereof when used as a digital still camera, thus making it possible to immediately understand which function the device is in.
In the above-described conventional technique (Japanese Patent Application Laid-open No. Hei 10-65780), it is disclosed that transmitted and received images are both displayed on one image display part of the portable telephone. However, a size of the image display part of the portable telephone is limited. Thus, when the single image display part is displayed by being divided, the area of the display part is reduced, thereby bringing about a possibility of exceeding a visual confirmation capability. Moreover, an actually transmitted image is processed to be reduced, and thus there is a problem that the actually transmitted image itself cannot be confirmed.
Moreover, in Japanese Patent Application Laid-open No. Hei 9-247250, liquid crystal displays are disposed on the back of the operating part and in the body. However, in this constitution, there is a problem that a major part of the liquid crystal display part of the lid body cannot contribute to display of information at all when the operation is performed while closing the lid body.
Furthermore, in the invention related to Japanese Patent Application Laid-open No. 2001-136247, the two display parts are merely in the state of being fixed to a surface of the portable telephone and to an internal surface of the folded part, respectively. Thus, an enlarged display screen cannot be formed in use of the portable telephone.
In the invention according to Japanese Patent Application Laid-open No. Hei 11-146370 related to the video telephone, the display region of the screen is fixed. Thus, similarly to the invention disclosed in Japanese Patent Application Laid-open No. Hei 10-65780, there is a problem that the actually transmitted image cannot be confirmed.